Conventionally, there has been known a detecting mechanism for detecting presence and absence of sheet staples ST stacked in a cartridge (not shown) as shown in FIG. 23.
The detecting mechanism is composed of an actuator 1 provided below the stacked sheet staples ST and a micro-switch 2. If the sheet staples are absent in the cartridge, the actuator 1 rotates about a shaft 3 in a clockwise direction and then the micro-switch 2 detects the clockwise rotation of the actuator 1, as a result, the presence and absence of the sheet staples ST are detected.
By the way, in such a detecting mechanism for the sheet staples, because the actuator 1 and micro-switch 2 are disposed below the stacked sheet staples ST, an electric staple cannot be miniaturized. In addition, in an electric staple having a driver unit and a clincher unit which are separated upwardly and downwardly, because a paper is passed between the driver unit and clincher unit, there is a problem that providing the detecting mechanism below the cartridge is difficult, and so on.
Moreover, a cartridge 5, as shown in FIG. 24, is provided with a roller 7 for sending sheet staples ST to a transport path 6. A driver DP and a forming plate FP are disposed movably upwardly and downwardly above a front end (left end region in FIG. 24) of the transport path 6 to form a staple in a U shape by lowering the forming plate FP and to drive out the formed U-shaped staple toward a sheet bundle T by lowering the driver DP.
Contained in a containing part 5A of the cartridge 5 is a case 8 in which the sheet staples ST are stacked, as shown in FIG. 25. The stacked sheet staples ST are combined by a tape TP which is removed at the time the sheet staples are contained in the containing part 5A of the cartridge 5.
In the cartridge 5, the lowest sheet staple ST is sent to the transport path 6 by the roller 7, while, if the sheet staple ST is curved in such a manner that a central portion thereof becomes convex below in their back and forth, because forward and backward ends of the sheet staple ST become in a raised state, and therefore there is a problem that the forward end is caught on an upper edge of an entrance of the transport path 6 and the sheet staple ST cannot be sent to the transport path 6.